The present applicant has previously applied for a patent for the general system for example in WO2012148351. As is known per se from this patent application, the system operates in cycles, each comprising the following steps:                evacuating the liquid from the associated feeding conduit after completion of a tapping operation at the associated liquid tap unit, by generating a backward pressure gradient in the associated feeding conduit, so that the liquid flows backwards towards the liquid source and the associated feeding conduit thereafter contains only air or gas being retained therein, and        refilling, upon activating said liquid tap unit, the associated feeding conduit with liquid by generating a forward pressure gradient in the associated feeding conduit and permitting liquid to flow from the liquid source to the associated liquid tap unit, while pushing the remaining air or gas in the feeding conduit towards the associated liquid tap unit at an operating pressure exceeding an ambient air pressure level.        
In the prior art system, as disclosed in the above-mentioned PCT application, each feeding conduit is connected to the liquid source by means of a single control valve, which can be open or closed. When it is open, the liquid source will feed liquid into the associated feeding conduit as long as the liquid tap unit signals that the flow of hot water should be maintained. When a tap unit is closed or deactivated, a signal is given so as to activate a centrally located pump which pumps back the liquid from the feeding conduit via the open control valve back to the liquid source. The same pump may be used for circulating hot water in the liquid source and for pumping back liquid from the feeding conduits. When a feeding conduit is completely evacuated, which is sensed by a level sensor, the control valve is closed again, so that the feeding conduit is retained at a relatively low pressure, slightly below the ambient air pressure, with only gas or air therein. Moreover, in the prior art system, air or gas will replace the liquid when it is evacuated from the feeding conduits. For this purpose, there is a special air valve adjacent to the liquid valve between the feeding conduit and the associated tap unit.
In order to have a smooth and practical function the applicant has improved parts of the previous system.